Manufacture of motor fuels



Dec. 23, 1941. A. R. GoLDsBY MANUFACTURE OF MOTOR FUELS Filed Aug. 4, 1938 [NVE/vra@ v .Affen/1J@ /Fbzy BY amm" was' AWORNEYS Parente'd Dec. 23, 1941 MANUFACTURE oF Moron FUELS Arthur R. Goldsby, Beacon, N. Y., assigner to Texaco Development Corporation, New York, N. Y., a corporation of Delaware Application August 4, 1938, Serial No. 222,996

13 Claims.

This invention relates to the manufacture of motor fuels and has to do particularly with the production of high antlknock gasoline hydrocarbons by the alkylation of isoparailins with olens in the presence of an alkylation catalyst.

In accordance with the invention, low boiling isoparaiiins are treated with olens in the presence oi' a catalyst having the property of effecting the alkylation of the isoparailins with the oleilns, wherein the reaction takes place over a substantial temperature range. 'I'he invention is particularly applicable to the treatment of isoparaflins, such as isobutane or isopentane, with normally gaseous olens or polymers thereof in the presence of a liquid catalyst, such as sulfuric acid, and preferably sulfuric acid of about 93 to 98% concentration, whereby branch chain saturated hydrocarbons of high antiknock value and within the gasoline boiling point range, are formed.

' current ilow type of process.

In the alkylation with such catalysts, there aviation gasoline hydrocarbons, is decreased. At

higher temperatures the deterioration of acid is greater but the yield of the desired hydrocarbons is increased. It is the normal practice to select an average constant temperature at which a satisfactory yield is obtained without excessive loss of catalyst.

It has been found that by carrying out the alkylation reaction over a graduated temperature range, it is possible to obtain more eflicient use of the catalyst and a higher yield of hydrocarbons, of the desired boiling point range and antiknock value. The improved results are vbelieved to be due largely to a more eilicient use of the acid as it becomes spent, whereas in a constant temperature operation, the acid becomes less emcient as the deterioration or concentration thereof decreases. According to'the method of the present invention, the emciency of the used acid may be maintained by 'increasing the temp'erature which compensates for the loss of activity due to deterioration.

The invention is not restricted to any particular type of operation although it is well adapted to a continuous process, such as, a concurrent flow, in which the catalyst and hydrocarbon are passed through a pluralityof stages, throughout which a graduated range of temperature is maintained. It is also contemplated that the oper- Referring to the drawing, there 'is shown a series of mixers I, 3, 5, 1 and 3, each equipped with stirring mechanisms and means for controlling the temperatures, such as heating coils. The mixers are connected in series by means of the lines 2, 4, 6 and 8. While live mixers or stages of reaction are shown, it is to be understood that any number may be used. The acid catalyst is introduced into the rst mixer through the line I2 by means o1' the pump I4. The hydrocarbon, comprising isoparaillns to be alkylated. is introduced through the line I5 in which is located pump I6. The oleiin charging stock is drawn through the line I8 by the pump I9 and may be charged into any one or all of the mixers I, 3, 5 and 1 through valve controlled manifoldvlines 2|, 22, 23 and 2l respectively. The hydrocarbon and catalyst pass concurrently through the series of mixers wherein the desired alkylation is effected.

The reaction products pass from the last mixer 3 through the transfer line 26, to a ilnal settler 21 wherein the acid and hydrocarbons are allowed to separate into two layers. The acid layer in the bottom may be drawn oli through the valve controlled line 28. The upper hydrocarbon layer is passed through the line 23 to a mixer 30 wherein the hydrocarbons are contacted with an alkaline neutralizing agent, introduced through the line 32 by the pump 33. The mixture of hydrocarbons and neutralizing agent is conducted through the line 34 to a settler 35 wherein the neutralizing agent is allowed to settle out and may be withdrawn from the bottom thereof through the valve controlled line 31 or recycled to the mixer through the line 33 which communicates with the alkali charging line A32.

The neutralized hydrocarbons are passed through the line 39 to fractionator 40 wherein the hydrocarbons of higher boiling point than butanes are fractionated out and withdrawn as vapor fraction, comprising the butane hydrocarbons and lighter, including normal and iso butane, is passedv overhead from the fractionator 40 through the vapor line M to a secondary fractionator I5. In'the latter fractionator the normal butane is fractionated out and withdrawn from` the lower portion oi' the fractionator through the line 46. The remaining normally gaseous hydrocarbons may be fractionated in the upper portion of the fractionator I whereby an isobutane side stream may be removed through the line 48 and the lower boiling normally gaseous hydocarbons removed overhead through the valve controlled line 50. When the hydrocarbons treated in the system comprise essentially C4 hydrocarbons, there may be substantially no products of lower boiling point than isobutane, and in such instance. the isobutane may be removed overhead from the fractionator I5 through the vapor line 5I. The isobutane .fraction removed as a side stream through the line 48 or overhead through the line 5I. as the case may be, is condensed in the condenser coil 52 and the condensate collected in the receiver 53. The isobutane condensate may be withdrawn from the receiver 53 through the line 54 and forced by the pump 55 into the initial mixer of the system.

The liquid product withdrawn from the bottom of fractionator 40 through the line I2 is passed to a fractionator or still 58 wherein the desired gasoline product is fractionally distilled and vapors thereof passed overhead through the vapor line 59 to a condenser 60. The resulting condensate is collected in the receiver 6I. The hydrocarbons of higher boiling point than gasoline are withdrawn from the bottom of fractionator 58 through the line 62. In some cases it may be desirable, in order to increase the volcracking stills:

Charge to stage:

No. 1 Isobutane Isobutane Isobutane plant gas. plant gas. plant gas. Plant gas.- Plant gas.. Plant gas. Plant gas Plant gas Plant gas. Plantgas Plant gas.. Plant gas.

Bl Blank Blank 62 61 64 62 6l 64 -62 6l 96 62 95 96 5 62 95 l06 Percent conc. of sulfuric acid.. 98. 3 98. 3 98. 3 Acid/olefin ratio 0. 58 0. 6 0. d Isobutane olefin ratio 3. 17 3. 24 3. 24 Contact t e, min 150 150 150 311 F. fraction:

Percent yield by weight basis of olefin 119. 7 127. 9 137. 5 Octane No. C. F. R. M 92. 2 91.6 91.8 Bromine No 1 1 1 311 F.400 F. fraction:

Percent yield by weight basis of olefin 24. 1 24.6 22. 5 Bromine No 1. 0 l 1. 5 Material balance. 95. 7 97. l 96.6 Percent H1504 in the recovered acid 86. 9 82.6 l 76. 0

The concentration of acid employed may vary, but with the various concentrations of acid, the temperatures will be different. When using about 98% acid, it is contemplated that the temperature gradient may be from about 60 to 105 F. With weaker concentrations of acid, however, the temperature should be increased.

Thus, with 94% acid the temperature range may 75 be from about '15 to 120 F., and with 90% acid from about to 130 F. Satisfactory results have been obtained with overall temperature gradients ranging from 40 to 60 F. Accordingly, when using a multiple stage unit containing five to ten stages, the temperature differential between the stages may be about 10 to 5, and a fairly uniform temperature variation may exist from stage to stage.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made Without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. In the alkylation of low boiling isoparaf'llns with olens to produce gasoline hydrocarbons wherein the hydrocarbons are contacted with strong sulfuric acid catalyst of alkylation strength while hydrocarbons and catalyst pass serially through a plurality of stages at reaction temperatures, the improvement which comprises maintaining the catalyst at a higher tempera' ture in the later stages than in the early stages' to increase the activity of the used catalyst in the later stages.

2. In the alkylation of low boiling isoparaiiins with olens to produce gasoline hydrocarbons wherein the hydrocarbons and fresh strong sul-1 furie acid catalyst of alkylation strength are passed through a multiple stage reaction zone from which spent acid and alkylation products are withdrawn, the improvement which comprises maintaining in that stage from which the spent acid is withdrawn, a higher temperaturethan in that stage to which the fresh acid 'ist charged.

3. In the alkylation of low boiling isoparafdns with olens in the presence of strong sulfuricacid of alkylation strength to produce gasoline hydrocarbons, the method comprising serially passing streams of hydrocarbon and acid through a multiple stage reaction zone wherein sufficient time and contact are provided to effect the reaction and increasing the temperature in the direction of ow of the acid through the successive stages to maintain a temperature differential between stages of about 5 to 10 whereby the eiiiciency of the acid is maintained substantially constant.

4. Asprocess for the manufacture of gasolinel hydrocarbons which comprises contacting low boiling isoparamns and olens with sulfuric acid of about to 94% concentration in a multiple stage reaction zone and maintaining a progressively increasing temperature in the direction of flow of the acid between 75 and 130 F. whereby the loss in efciency in the acid is substantially prevented.

5. In the manufacture of gasoline hydrocarbons by the alkylation of low boiling isoparaflins with olens in the presence of sulfuric acid of about 90-98% concentration as an alkylation catalyst, wherein the catalyst decreases in coneentration and loses its eiliciency during the operation, the improvement which comprises progressively increasing the temperature to obtain a temperature gradient within the range of about 60-130 F. during the operation to compensate for loss in efficiency of the catalyst as it becomes spent. l

6. In a continuous process for the alkylation uously bringing the catalyst and hydrocarbons together in a reaction zone, wherein the catalyst tends to deteriorate and cause loss in yield during the operation, the improvement which comprises raising the temperature within range of about 60-l30 F. as the catalyst deteriorates within the range of .9B-98% to maintain the activity of the deteriorated catalyst and avoid loss in yield.

7. In a continuous process for the alkylation of hydrocarbons wherein low boiling isoparamns and oleflns are contacted with strong sulfuric acid of alkylation strength while the acid and hydrocarbons are passed serially through a multiple stage reaction zone under conditions of time and temperature suilicient to produce gasoline hydrocarbons. the method of increasing the eiliciency of the acid which comprises maintaining the temperature of the acid at a succeeding stage of the stream higher than at a preceding stage of the stream in said zone.

8. In a continuous process for the alkylation of hydrocarbons, wherein low boiling isoparaiiins and oleiins are contacted with strong sulfuric acid of alkylation strength while the acid and hydrocarbons are continuously passed through an elongated reaction zone, under conditions of time and pressure suilicient to produce gasoline hydrocarbons and Ithe acid deteriorates and loses eiciency during the reaction, the method of compensating for loss in efnciency of the acid by deterioration, which comprises maintaining the used acid leaving the reaction zone at a higher temperature than the feed acidby progressively increasing the temperature of the acid as it passes through said reaction zone.

9. In the alkylation of low boiling isoparaiiins with oleins to produce gasoline hydrocarbons, wherein the hydrocarbons are contacted with strong sulfuric acid of alkylation strength in a sectional reaction zone, the-improvement which comprises contacting hydrocarbons with fresh acid in one section of said zone and with partially spent acid in another section of said zone and maintaining a higher temperature in that section wherein the hydrocarbons contact the partially spent acid than in that section wherein the hydrocarbons contact the fresh acid to increase the eiiiciency of the partially spent acid.

10. In the alkylation of low boiling isoparafiins with olens in the presence of strong sulfuric acid of alkylation strength to produceI gasoline hydrocarbons, the steps of passing serially the acid and hydrocarbons through a plurality of reaction zones and maintaining a rising temperature gradient totaling about 40 to 66 F. in the acid in the direction of flow thereof through said zones.

11. A process for the alkylation of low boiling isoparamns with olelns, which comprises serially passing a mixture of isoparafns and strong sulfuric acid through a plurality of reaction zones, contacting the mixture in said zones with olens while maintaining an excess of isoparafiins over the olei'lns, and progressively increasing the temperature of said mixture iiowing through the consecutive zones to compensate for loss of the eiiiciency of the acid by deterioration.

12. A process for producing alkylated hydrocarbons by the interaction of isoparaiilns and olens, which comprises reactingthe hydrocarbons to be alkylated with the oleiins in contact with strong sulphuric acid and at optimum pressures and temperatures, and increasing the reaction temperature as the strength of the stron sulphuric acid decreases.

13. In the alkylation of low-boiling isoparains with oleilns in the presence of strong sulfuric acid of alkylation strength to produce gasoline hydrocarbons, wherein the acid ows -serially through at least two alkylation reaction zones where hydrocarbons are charged, the improvement which comprises maintaining a prior zone in the direction of flow of the acid at a lower temperature than a succeeding zone.

ARTHUR R. GOLDSBY. 

